Light sensitive film or carrier therefor



Sept- 19, 1933- w. T.' L.. BECKER ET AL LIGHT SENSITIVE FILM 0R CARRIER THEREFOR Filed April 27. 1929 Il cm Patented Sept. 19, 1933 UNITED STATES PATENT OFFCE 'LIGHT sENsrrIvE FILM on CARRIER.

.THEREFOR Application April 27, `1929, Serial No. 358,749, and in Great Britain May 26, 1928 16 Claims.

This invention relates to the production of photographic images upon sheets of transparent material of the kind which are permeable to water, expand'when wetted and are capable of being handled or treated when wet in an unsupported statethat is to say, sheets other than mere layers adhering to supports of glass, celluloid or the like and incapable of being handled apart from their supports.

The object of the invention is to provide a method whereby photographic images of a predetermined size may be produced upon such sheets notwithstanding their tendency to expand when wetted and thereafter to contract on drying to indeterminate extents depending upon the treatments to which they may be subjected while wet.

The invention is particularly applicable and useful in the preparation of coloured images to be combined together to form natural-colour photographs according to the subtractive method, although it has other applications. Owing to the above-mentioned properties of these materials, it has hitherto been a matter of the utmost difficulty consistently to obtain images of the same size. Consequently, the accurate registration of a number of images in superposition has been impossible, and processes based upon the use of such permeable materials have been of little practical value, although their permeability has offered great advantages in the subtractive process owing to the ease with which the sheets may be combined by means of aqueous adhesives.

d We have found that cellophane sheets when fully saturated with water tend to expand to a definite maximum size and when fully dry tend to contract to a minimum size. The sheets may assume any intermediate state of expansion between this maximum and minimum, but unless they are stretched or compressed by the application of external force, they do not of their own accord tend to exceed such maximum dimensions nor to contract below such minimum dimensions.

When fully saturated with an aqueous solution, the sheets expand to approximately the same normal maximum but upon drying they do not contract to the same normal minimum which would be attained upon drying after immersion in pure water. Our observations have led us to conclude that in the case of a cellular or photoplasmic material impregnated with a solution the minimum size attained when fully dry is determined by the state of contraction or' distension of the component cells, which state of distension is influenced by the amount of solid matter retained within the cells after evaporation of the impregnating solvent. Thus the state of expansion of such a material seems to be dependent upon the amount of solid and/or liquid material trapped within its substance. Thus, when three sheets of similar permeable material are coated or impregnated with different solutions (such as those suitable to give images in magenta, blue-green and yellow, for use in three-colour photography), and the three sheets are dried, each sheet tends to assume a diierent state of relative contraction by reason of the different amounts of solid matter contained in the several solutions, and also to some extent by reason of the diiering hygroscopjc qualities of the chemicals employed.

If images of identical dimensions be now impressed upon the three sheets, and the sheets be subsequently immersed in a bath of liquid (as for.` the purposes of fixing) all the sheets will expand to the same maximum state. But as the images were `not impressed when the sheets were in the same state of relative expansion, the images will not be of equal size when the three sheets have attained a similar condition of maximum expansion, and consequently it will be impossible to make the three images register.

If, on the contrary, after fixing, the three sheets bearing the impressed images be allowed to dry, they will contract to varying extents depending upon the nature of the xing solution and of the chemical changes which have taken place in xh ing. In any case, the precise conditions which were present when the images were impressed are not likely to be again reproduced with like results except by chance, and the dry images will usually again dier in size so that registration will be imp'ssible except by stretching.

When it is desired to produce a composite picture or transparency by the superposition of images, it is usually desirable to effect the superposition when the several layers are wet, partly because it is convenient to complete the picture without delay after xing and washing the several layers, and also more particularly because in the wet state they are more easily pressed into intimate contact. In the wet state the sheets are in a similar state of maximum expansion, and in order that the several images may then register the fully wet images must clearly be of equal size.

In order to elect this it is essential that the images should be impressed upon the sheets when the component sheets of any picture are in similar states of expansion. The precise meaning of similar states of expansion may be illustrated by a numerical example, reference being made to the accompanying drawing in which Figures 1 to 6 are diagrammatic illustrations showing the expansion and contraction of sheets undergoing treatment.

Let it be assumed that a linear expansion of 10% takes place upon wetting a dry sheet of pure cellophane C (Fig. 1). Let two points A and B be marked upon the dry sheet C, the distance AB being" 10 cm. Upon fully wetting C the distance AB will become AB=10 cm.+10%=11 cm.

Let three similar sheets C1, C2, C3 bearing marked points A1 B1, A2 B2, fh Ba, be immersed in three 'different solutions. Initiallyr A1 B1: A2 B2=A3 B3=l0 cm. (Fig. 2) and after immersion A1 B1'=A2 B2V=Aa Bs=11 cm. (Fig. 3) and they are in equal states of expansion. If after immersion in different solutions and drying A1 B1"=A2" B1"=A1" B3"=say 10.5 cm. (Fig. 4) the sheets would still be in similar states of expansion. But in practice after immersion in different solutions and subsequent drying it would probably be found that A1" B1=10.2 cm. A1" B2"=10.4 cm. A3" B1=10.6 cm. (Fig. 5) and the sheets would not be in similar conditions of expansion.

If at this stage images X1 Y1=X2 Y2=Xa Ya=5 cm. (Fig. 5) be impressed upon the sheets, and the sheets again be made fully wet for the purpose of superposition of the images, each sheet would expand to its original maximum of A1'" B1'=Az B2=A3' B3"'=l1 cm. and each image would expand in the same proportion as its carrier sheet. Thus the dimensions of the images borne by the respective sheets would be as follows:-

C3; X3'Y3'=X5 cm.=5.18 cm. A

and they would be incapable of registration (Fig. 6).

If on the other hand A1" B1"=Az" B2=A3" B3=l0.5 cm. as illustrated in Fig. 4. When the images are impressed the expanded images on the several sheets would clearly be of equal sizes, and would be capable of registration.

According to the present invention each sheet t is first treated to bring it to and maintain it when dry in a state of expansion, bearing a definite predetermined ratio to its state of maximum expansion as hereinbefore defined, and the image is impressed upon'the sheet while so maintained.

To put into practical effect this invention whereby images of a desired size may be obtained we employ different methods each having particular advantages.

In one method, the permeable carrier sheet is coated or impregnated with suitable colour forming or sensitizing or other solution, being made sufficiently wet to cause it to attain a known ly soluble in the impregnating or coating solution.

Normally, the image is in either case impressed upon the sheet while it is in adhesive contact with the support, after which the support and sheet may be soaked and the sheet bearing the image removed from the support. But in certain cases it -is convenient to strip the sheet from its support in the dry state and to impress the image upon the sheet after stripping. We nd that the dry sheet if kept under suitable conditions does not normally change its condition of expansion after such stripping, the tendency to contract ceasing when it has once become dry.

Wel have found that certain varieties of cellophane tend to expand unequally when wet, that is to say, the lateral expansion may be greater than the longitudinal expansion. This difference of expansion for many purposes may be ignored, but in the reproduction of geometrical objects some slight distortion may be apparent. It is an advantage of this method that by mounting the sheet upon a support, such unequal expansion is overcome or provided for.

We have found that by adjusting the amount of the solid contents in the sensitizing solutions, it is possible so to control the contraction of. the sheets upon drying after sensitizing, that similar sheets impregnated with different solutions, remain under normal conditions in equal states of expansion or contraction. By normal conditions we mean normal conditions of atmospheric humidity and temperature. If now images be impressed lupon the dry sensitized sheets, they will upon immersion all expand equally and will be capable of registration without difliculty.

In practice, itis not usually convenient or practicable to vary the sensitizing or colour forming contents of such solutions within the limits required to control the contraction and expansion of the sheets, and we prefer independently to control such contraction or expansion by adding to the different solutions varying quantities of inert soluble substances such as sugar or glycerine. v

In the case of cellophane, we usually control the expansion and contraction by the addition of from 1% to 15% of cane sugar, the precise amount being very easily determined by experiment in any particular case. We have found thatI cane sugar is particularly suitable for use with cellophane by reason of the facility with which its solutions diffuse through permeable cellulose membranes, and by reason of the fact that in negative materials for general photographic purposes, cinematography, copying of line drawing and the like.

We claim:

l. In a process of subtractive multi-color photography in which a set of mono-colored partimages of the same subject on separate sheets are superimposed in register to form a composite picture in natural colors, a method of preparing the component sheets to receive the part-images, which consists in sensitizing an appropriate number of sheets of water-permeable transparent material of the cellophane type with different solutions respectively and treating the sheets in a wet condition in such manner as to control their contraction upon drying to a degree such that all the sheets of the set will, when dry, be in the same state of relative contraction.

2. In a process of subtractive multi-color photography in which a set of mono-colored partimages of the same subject on separate sheets are superimposed in register to form a composite picture in natural colors, a method of preparing the component sheets to receive the part-images, which consists in sensitimng an appropriate number of sheets of Water-permeable transparent material of the cellophane type with different solutions which have varying eiects upon the degree of contraction, on drying, of the several sheets, and compensating for such varying eiects by controlling the contraction of the sheets by treatment of them While wet in such manner as to ensure that when dry all the sheets of the set will be in the same state of relative contraction from their maximum expanded state.

3. In a process of subtractive multi-color photography in which a set of mono-colored parti'mages of the same subject on separate sheets are superimposed in register to form a composite picture in natural colors, a method of preparing the component sheets to receive the part-images, which consists in sensitizing an appropriate number of sheets of water-permeable transparent material of the cellophane type with different solutions, bringing all the sheets into the same state of expansion, causing the sheets to adhere in a Wet condition to substantially inextensible supporta-drying the sheets while so adhering and thereafter removing them from the supports.

d. In a process of subtractive multi-color photography in which a set of mono-colored partimages of the same subject on separate sheets are superimposed in register to form a composite picture in natural colors, a method of preparing the component sheets to receive the part-images which consists in expanding the sheets by wetting so that they are all in the same state of relative expansion, causing the sheets to adhere in their aforesaid wet expanded condition to substantiali ly inexltensible supports, selectively treating the sheets while on their supports with different sensitizing solutions, thereafter drying the sheets while still on their supports and nally removing the dried sheets from their supports.

5. In a process of subtractive multi-color photography in which a set of mono-colored partimages of the same subject on separate sheets are superimposed in register to form a composite picture in natural colors, a; method of preparing the component sheets to receive the part-images, which consists in sensitizing an appropriate number of sheets of water-permeable transparent material of the cellophane type with diierent solutions which have varying eiects on the degree of contraction on drying of the several sheets, and

compensating for such varying effects by controlling the contraction of the sheets by selectively treating them while wet with a pore-liing substance in s uch manner that all the sheets of the set will when dry be in the same state of relative contraction.

6. In a process of subtractive multi-color photography in which a set of mono-colored partimages of the same subject on separate sheets are superimposed in register to form a composite picture in natural colors, a method of preparing the component sheets to receive the part-images, which consists in sensitizing an appropriate number of sheets of water-permeable transparent material of the cellophane type with different sensitizing solutions containing inert pore-lling substances so adjusted as to concentration with respect to the particular sensitizing solution that the contraction of the several sheets will be conrolled to ensure that all the sheets of the set when dry Will be in the same state of relative contraction.

7. In a process of subtractive multi-color photography in which a set of mono-colored partimages of the same subject on separate sheets are superimposed in register to form a composite picture in natural colors, a method of preparing the component sheets to receive the partimages, which consists in sensitizing an appropriate number of sheets of water-permeable transparent material of the cellulose type with different solutions and simultaneously impregnating selected sheets with 'an inert pore-lling substance of such concentration with respect to the particular sensitizing solution as to control;

the degree of contraction, on drying, of the sheets to ensure that all the sheets of the set will when dry be in the same state of relative contraction.

8. In a process of subtractive multi-color photography in which a set of mono-colored partimages of the same subject on separate sheets are superimposed in register to form a composite picture in natural colors, a method of preparing the component sheets to receive the partimages, which consists in sensitizing an appropriate number of sheets of water-permeable transparent material of the cellophane type with different sensitizing solutions to which sugar has been added in such concentration as to control the degree of contraction of the sheets, on drying, to ensure that all the sheets of the set will whenH dry be in the same state of relative contraction.

9. A'methcd of preparing a natural-,color photogra'ph* by the superimposition of a plurality of diilerently colored images which comprises sensitizing, with different solutions appropriate to the diierent colored images, a plurality of sheets of water-permeable transparent material of the cellophane type, bringing the sheets While wet into a condition such that they will dry to the same relative degree of contraction, drying these s'heets, and by known steps producing developed colored images thereon, and superimposing these sheets in register While wet.

10. A method of preparing a natural-color photograph by the superimposition of a plurality of differently colored images which comprises sensitizing, with different solutions appropriate to the different colored images, a plurality of sheets of water-permeable transparent material of the cellophane type, bringing the sheets while wet into the same state of expansion, causing the sheets to adhere in a wet condition to substantially inextensible supports, drying the sheets fil while so adhering and thereafter removing from the supports aforesaid, producing by exposure latent images of the same subject on the several sheets, developing these 'lat ent images, and thereafter superimposing the sheets in register to form the composite picture.

v11. A method of producing a natural-color photograph for the superimposition of a plurality of diierently colored images of the same subject,-which comprises sensitizing a set of sheets of water-permeable transparent material of the cellophane type with different sensitizing solutionsA which are appropriate to the diierently colored images and which have varying eifects on the degree of contraction on drying of the several sheets, compensating for such varying eects by controlling the contraction of the sheets by selectively treating them while wet with a pore-filling substance in such manner that all the Asheets `of the set will when dry be in the same state of relative contraction, drying the sheets and by exposure producing thereon latent images -of the sarne subject, developing these images, and finally superimposing the sheets in register while wet.

12. A method of producing 'a natural-,color photograph by the superimposiiton of a plurality of differently colored images which consists in impregnatng a set of sheets of Water-permeable transparent material' of the cellophane type with different sensitizing solutions appropriate to the differently colored images and containing inert pore-filling substances so adjusted as to concentration with respect to the particular sensi- 'tizing solutions that the contraction of the several sheets will be controlled to ensure that all same state of relative contraction, drying the sheets and by exposure producing latent images' thereon of the same subject, developing such latent images, and finally superixnposingthe'. several sheets in register while wet.

13. A process of substractive three-color -photography in which three mono-colored part-images of the same subject are superimposed in register to form a composite picture in natural colors, which process consists in sensitizing three sheets of cellophane with different sensitizing solutions which are appropriate respectively to the colors of the part-images and which have varying eiects on the degree of contraction on drying of the three sheets, compensating for such varying eiects by so controlling the shrinkage capacity of the sheets as to bring all three sheets, when dry, into the same stateof relative contraction, producing by exposure latent images of the same subject on the three sheets, printing out these latent images in the three mono-colors, and finally superimposing the three image-bearing sheets in register.

14. A process of substractive three-color photography, in which three mono-colored partimages of the same subject are superimposed in register to form a composite picture in natural colors, which consists in sensitizing three sheets Aof cellophane with different solutions adapted to give prints in magenta, yellow and blue-green respectively, impregnatng selectedv sheets with inert pore-filling substances of such concentration with respect to the particular sensitizing solution as to rcontrol the degree of contraction, on drying, of the sheets to ensure that all three will when dry be in the same state of relative contraction, exposing the sheets to produce latent imageslof thesame subject thereon, developing such latent images and finally superimposing the three image-bearing sheets in register while wet.

15. For the production .of a natural-color phowetted, and is capable of being handled or treated When Wet in unsupported state, said sheets being impregnated with different sensitizers appropriate .to the different colors of the part-images and all .being capable of the same degree of maximumA the sheets of the set, when dry, will be in the l expansion when wetted, and being when dry in the same state of relative contraction from that maximum.

16. For the production of a natural-color photog'raph by the superimposition, in register, of three mono-colored part-images of the same subjet'c, a set of 'three sheets of cellophane impregnated with different sensitizers appropriate to the three mono-colors of the part-images and all being capable of the same degree of maximum expansion when wetted, and being when dry in the same state of relative contraction from that maximum.

WHJFRED TREVOR LEIGH BECKER. LESLIE WALTER OLIVER. 

